You've got that right.

 

Not sure where you got this from? I have a 5.4 4x4 and it's never once gotten up to 15mpg. It normally gets 12.

 

X2 my 4.2L gets 21mpg avg.

 

My 5.4 Screw get 15.5 on average. By the old school method of dividing miles traveled by gallons pumped (one click everytime). My dad's 2003 Expy gets 15 with the 5.4. In his old 4.6 Expy He would average around 17 with mostly highway driving. MPG can vary depending on a lot of factors, including how the person driving does the math. If I drive all city I get 13 in my 5.4. With a 50/50 mix you should see around 15ish with the 5.4, 16-17 with the 4.6. If you are getting 21 with the 4.2 then either you must have gotten the pick of the litter because it would be the first F150 I've every heard of getting better MPG than what the EPA sticker says on the highway (which are usually only real in a dream.)

I compared my average MPG on my last 3 vehicles to the stats here at http://www.fueleconomy.gov/feg/sbs.htm and was surprised to how accurate they were.

 

My 4.2 does very well on the highway too. I would say it averages 20+mpg on the flat highway at 55-65. It sucks on the gas in the city though, mostly because of my underpowering highway gearing.

 

I think that 20 or more is very doable on the highway, but to average 21 overall would mean the V6 is getting at least 25 on the highway. Unless you do 90-100% highway driving at 60 mph, I am waiving the BS flag on the 21+ mpg average.

 

I have a V6 4.2 and never got close to 20mpg that was before mods

 

So, BOO 71, what kind of MPG are you seeing?

 

Well just yesterday I loaded up a hammond b-3 cutaway,the b-3 amp/pedal box,leslie 147 speaker, a korg digital piano in an old heavy skb case,mic boxes,cables,stands bench,piano amp-total weight around 750 lbs..Drove 48 miles country highway and roads and according to the scangauge the 4.2 was getting 24.5 mpg @60 mph on cruise, and about an average of 10 mpg from a stop to cruising speed.Now back and forth to work I was getting around 19 mpg for the week on a 74 mile round trip each day on calm clear days,winter driving saw around 17.5 to 18 mpg average on mild winter weeks,and 14.5 mpg average on nasty winter weeks with wind and snow.I put 35,000 miles on the truck in 17 months so now I drive a 94 ford escort lx back and forth to work and it is averaging 33.6 mpg doing the math per fill-up.
So now the truck sits in the garadge until I need to tow,pull,or move a load.I feel the 4.2 is plenty strong with the troyer tunes.So I'm happy with the truck but pissed off at the oil company,gouging,blood thirsty sob's that are controlling the gas prices!

 

4.2l is a great engine. I am a bit surprised that it doesn't get over 21 mpg in the HWY

 

my friend is twin turboing his V6 03 reg cab, he had the whole engine rebuilt, but it is not cheap

 

Sounds like the potential is there for decent MPG if you run at 60 with the cruise on. But it sounds like when you are driving more realisticly on your highway commute you are avg 19? There is nowhere to run 60 here. On the interstate you better be doing at least 75 if you don't want someone to shoot at you. Usually 80-90 range. How does doing the math compare to the readout on the scanguage? I am really considering getting one of these for myself. I fell sure I am getting about 12-14 MPG at 80-90 MPH.

 

"How does doing the math compare to the readout on the scanguage? I am really considering getting one of these for myself. I fell sure I am getting about 12-14 MPG at 80-90 MPH."
Well the scangauge can be adjusted to match the math in the fuel section,so when you set it up after the first fill(adjust the gauge) then the math is dead on when you read the gauge while it is rolling.At first it was 1.7% off and when I readjusted the setting it now reads pretty darn close to dead on.
The average for driving to and from work was driving 70 to 85 mph on the highway sometimes 90 when I sleep to long.City driving kills the mileage in these trucks with the 4.2.Once you hit your cruise speed it gets great mileage it just sucks it fast comming off lights, or from any stop for that matter.
Get the scangauge 2 it looks better and does a little more!!!